What common reasons given for inducing labor are not supported by research?
For a surprising number of conditions, the effectiveness of induction has not been proven.Mozurkewich, E., Chilimigras, J., Koepke, E., Keeton, K., & King, V.J. (2009). Indications for induction of labour: A best-evidence review. BJOG, 116(5), 626-636. Yet many women with these conditions have induced labor because they believe it will be good for them or their babies. More research is needed to confirm the benefits and harms of induction in these situations:
- Preterm prelabor rupture of the membranes (PPROM): In this situation, the membranes break on their own before pregnancy week 37, and labor has not begun. Eight studies with a combined total of 1,230 babies of women with ruptured membranes between 34 and 37 weeks of pregnancy found no advantages for induction compared with waiting for labor with respect to C-section or infection or breathing problems in babies.
- Twin pregnancy: A single, small randomized controlled trial compared routine induction at 37 weeks with waiting for labor and found no differences in important health outcomes. More research is needed.
- Gestational diabetes requiring insulin: One trial looked at the outcomes of 200 women randomized to either be induced at 38 weeks or wait for labor. Those who waited were more likely to have large babies. There were no differences in health outcomes for the mothers or babies. The trial may have been too small to detect these differences.
- Intrauterine growth restriction (IUGR) at term: In this situation, the baby appears to be smaller than we would expect at or beyond 37 weeks of pregnancy. Two trials involving a combined 683 women found no benefit or harm to induction for suspected IUGR at term. More and larger trials are needed.
- Oligohydramnios (too little amniotic fluid): A single, small randomized controlled trial compared induction of labor with watching fetal well-being closely until 42 weeks for women with suspected low amniotic fluid at 41 weeks. The women were healthy and did not have other risk factors or complications. The study found no difference in maternal or newborn outcomes, but was too small to detect some important differences that may exist. No trials of induction for low fluid levels in women with otherwise healthy pregnancies at other gestational ages were found.
For other conditions, the available evidence suggests induction is ineffective, harmful or both.Mozurkewich, E., Chilimigras, J., Koepke, E., Keeton, K., & King, V.J. (2009). Indications for induction of labour: A best-evidence review. BJOG, 116(5), 626-636. Despite the research, many providers continue to recommend induction because:
- They believe the baby will get too big (suspected macrosomia). According to a systematic review of several studies involving more than 3,700 women, inducing labor when the provider suspects that the baby is large does not improve neonatal (baby’s) outcomes and appears to increase the chance that the woman will have a C-section.
- There is intrauterine growth restriction before 37 weeks. In this situation, the baby appears to be smaller than we would expect before pregnancy week 37. A large, multi-center randomized controlled trial of more than 1,000 women with growth-restricted fetuses between 24 and 36 weeks and abnormal Doppler artery blood flow showed that induction increased the likelihood of C-section. In addition, babies born before 31 weeks in the induction group were more likely to have severe disabilities at age 2 than babies born before 31 weeks in the group that waited for labor.